Full depth laser ophthalmic surgical system, methods of calibrating the surgical system and treatment methods using the same

ABSTRACT

A full depth ophthalmic surgical system includes a femtosecond laser source and an optical coherence tomographer. The system is capable of performing surgical procedures along the entire length of the eye from the cornea to the retina. In one embodiment, the system uses a removeable focal point extension assembly to extend the reach of the focal point location of the laser beam to the vitreous humor of the eye. In another embodiment, the optical system of the ophthalmic surgical system is optimized to focus the laser beam and imaging light in the vitreous humor of the eye. For procedures performed posterior to the lens, a method for calibrating the full depth ophthalmic surgical system uses the focal zone of the optical coherence tomographer beam as a proxy for the focal zone of the femtosecond laser source to. The system can be used to perform treatment in the vitreous humor, including treating floaters and liquification of the vitreous humor.

FIELD OF THE INVENTION

This disclosure is generally related to laser eye surgery, and morespecifically to laser eye systems and methods for treating vitreoushumor including ocular floaters.

BACKGROUND

Vitreous floaters are small particles consisting of cells, pigment, orfibrin that move in the vitreous of the eye. Patients with opaquevitreous humor floaters can suffer from blind spots and deterioratedvision. Vitreous surgery can improve visual acuity in these patients.Traditionally, vitreous surgery (vitrectomy) was performed by cuttingthe eye to remove the floaters with mechanical surgical tools, such as avitreous infusion suction cutter that cut the vitreous and removed thedebris from the eye by suction. Other vitrectomy methods have includedusing a nanosecond pulsed laser to tediously steer the laser visually totreat the floaters, thereby subjecting the retina to shock waves,mechanical distortions, as well as direct laser exposure of energylevels needed to treat the floaters effectively.

SUMMARY OF THE INVENTION

The techniques and systems disclosed herein provide many advantages overthe current standard of care.

In one aspect, the present invention provides a full depth ophthalmicsurgical system for performing surgery on eyes of subjects whichincludes: a femtosecond laser source configured to produce a pulsedlaser beam; an imaging assembly comprising an optical coherencetomographer; a scanning assembly for deflecting the laser; a firstpatient interface device configured to engage an eye of a subject andconfigured to be removably connected to the scanning assembly, the firstpatient interface device having a first predefined optical power, asecond patient interface device configured to engage an eye of a subjectand configured to be removably connected to the scanning assembly, thesecond patient interface device having a second predefined optical powerwhich is less positive or more negative than the first predefinedoptical power, the first patient interface and the second patientinterface being alternatively connected to the scanning assembly; and acontroller operably connected to the laser source, imaging assembly andscanning assembly and programmed to: operate the optical coherencetomographer to scan an imaging beam in a first eye in a first regionincluding a lens of the first eye and structures anterior to the lenswhen the first patient interface is engaged with the first eye andconnected to the scanning assembly, thereby obtaining image informationcorresponding to the first region of the first eye; operate the scanningassembly to scan a focal spot of the laser beam in the first region ofthe first eye to treat a tissue in the first region when the firstpatient interface is engaged with the first eye and connected to thescanning assembly; operate the optical coherence tomographer to scan animaging beam in a second eye in a second region including structuresposterior to a lens of the second eye when the second patient interfaceis engaged with the second eye and connected to the scanning assembly,thereby obtaining image information corresponding to the second regionof the second eye; and operate the scanning assembly to scan a focalspot of the laser beam in the second region of the second eye to treat atissue in the second region when the second patient interface is engagedwith the second eye and connected to the scanning assembly

Each of the first and the second patient interface includes: a bodyhaving an upper end and a lower end; wherein the upper end is configuredto be removably attached to an objective lens assembly of the ophthalmicsurgical system; a flexible suction ring disposed at the lower end ofthe body, configured to engage the eye via a vacuum force; and anoptical assembly disposed within the body and having the respectiveoptical power. The optical assembly is preferably a doublet lens.

In another aspect, the present invention provides a full depthophthalmic surgical system for performing surgery on an eye of asubject, which includes: a femtosecond laser source configured toproduce a femtosecond pulsed laser beam; an imaging assembly configuredto emit an imaging beam; a scanning assembly including a Z scanner andan XY scanner, configured to scan a focal spot of the laser beam and theimaging beam within the eye in a depth direction and two transversedirections, respectively; an illumination light source configured toemit an illumination light; a video camera assembly; an objective lensassembly configured to focus the laser beam and the imaging beam; apatient interface configured to be coupled to the objective lensassembly and to engage the eye, the patient interface including a lenshaving a predefined optical power; and optical components including atleast one beam splitter, configured to direct the laser beam and theimaging beam output by the scanning assembly and the illumination lightto the objective lens assembly, and to direct light emitted from withinthe eye, which has passed through the objective lens assembly, to thevideo camera assembly; wherein the scanning assembly, the objective lensassembly and the lens of the patient interface are configured to form afocal spot of the laser beam at any depth within a range of 15 mm to 24mm in water beyond a distal surface of the lens of the patientinterface. The video camera assembly includes a detector and a tunablelens in front of the detector, and wherein the tunable lens of the videocamera assembly is configured to focus light emitted from any distancewithin a range of 8 mm to 29 mm in water beyond the distal surface ofthe lens of the patient interface. The system further includes afixation light source configured to generate a fixation light, whereinthe optical components are further configured to direct the fixationlight to the objective lens assembly. The XY scanner includes twoscanning mirrors, wherein the objective lens assembly and the lens ofthe patient interface are configured to form respective images of thetwo scanning mirrors at locations 0 to 10 mm from a distal surface ofthe lens of the patient interface.

In another aspect, the present invention provides a method for treatinga vitreous humor of an eye of a subject using a laser ophthalmicsurgical system, the ophthalmic surgical system including an ultrafastlaser system, an optical coherence tomographer, and shared opticalcomponents, the method including: operating the shared opticalcomponents to scan a focal zone of a light beam of the optical coherencetomographer in a region of the eye posterior to a lens of the eye;detecting an intensity of the light beam after it is reflected from theeye; determining a depth of a retina of the eye based the detectedintensity of the reflected light beam; setting a first safe limitingdepth which is at a predetermined distance from the depth of the retinain an anterior direction; determining another depth of another structureof the eye based the detected intensity of the reflected light beam;setting a second safe limiting depth which is at another predetermineddistance from the depth of the other structure in a posterior direction;and based on the first and second safe limiting depths, operating theshared optical components to scan a focal zone of a laser beam of theultrafast laser within a volume of the eye between the first safelimiting depth and the second safe limiting depth. The other structureof the eye may be a posterior lens capsule.

In another aspect, the present invention provides a method of liquefyingthe vitreous humor of the eye, which includes irradiating at least aportion of the vitreous humor of the eye with a laser beam emitted froma laser source, the laser beam comprising laser pulses having awavelength of 1000-1100 nm, a pulse width of 100-1000 fs, a pulse energyof 2-20 μJ, a repetition rate of 1-500 kHz, and a total energy of lessthan 40 J.

This summary and the following detailed description are merelyexemplary, illustrative, and explanatory, and are not intended to limit,but to provide further explanation of the invention as claimed.Additional aspects, features, objectives and advantages of the inventionwill be set forth in the descriptions that follow, and in part willbecome apparent from the written description, taken in conjunction withthe accompanying drawings, illustrating by way of example the principlesof the invention, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the optical beam scanning system.

FIG. 2 is an optical diagram showing an alternative beam combiningscheme.

FIG. 3 is a schematic diagram of the optical beam scanning system withan alternative OCT configuration.

FIG. 4 is a schematic diagram of the optical beam scanning system withanother alternative OCT combining scheme.

FIG. 5A is a frontal view of a removable focal zone extension adapterconfigured to extend the focal zone of the optical beam scanning systemof FIGS. 1-4 so that the focal zone can extend into the portions of theeye posterior to the lens capsule.

FIG. 5B is a sectional view of the focal zone adapter of FIG. 5A.

FIG. 6 schematically illustrates an exemplary optical system that canscan the laser beam and the imaging beam within the full range of theeye from the cornea to the retina.

FIG. 7 schematically illustrates the laser light being focused in thevitreous humor of the eye using the optical system of FIG. 6.

FIG. 7A schematically illustrates scanned laser beams being focused intothe lens of the eye by a conventional optical beam scanning system inconjunction with a patient interface lens.

FIG. 7B schematically illustrates scanned laser beams being focused intothe vitreous volume of the eye by the conventional optical beam scanningsystem in conjunction with another patient interface lens.

FIG. 7C schematically illustrates scanned laser beams being focused intothe vitreous volume of the eye by an optical beam scanning systemaccording to an embodiment of the present invention in conjunction witha patient interface lens.

FIG. 8 is an image of the structures of the posterior portion of the eyeusing the OCT beam.

DETAILED DESCRIPTION OF THE INVENTION

The techniques and systems disclosed herein provide many advantages overthe current standard of care. Specifically, a removeable focal pointextension assembly used with an existing laser ophthalmic surgicalsystem provides a full depth ophthalmic surgical system capable ofperforming surgical procedures along the entire length of the eye fromthe cornea to the retina. A method for calibrating the full depthophthalmic surgical system for procedures performed posterior to thelens, by using the focal zone of the optical coherence tomographer beamas a proxy for the focal zone of the femtosecond laser source, providesa fast and efficient calibration methods that can be done for eachindividual patient. A treatment method and system performed in thevitreous humor achieves liquification of the vitreous humor, whichallows floater inclusions to move to a location where the central fieldof view of the eye is not affected by the floater, without disturbingother structures.

The present invention can be implemented by a system that projects orscans an optical beam into a patient's eye 68, such as system 2 shown inFIG. 1 which includes an ultrafast (UF) light source 4 (e.g. afemtosecond laser, or a dual purpose system capable of emitting pulsesin a lower and in a higher range of pulse energies, perhaps withdifferent pulse durations). Using this system, a beam may be scanned ina patient's eye in three dimensions: X, Y, Z. In this embodiment, the UFwavelength can vary between 1010 nm to 1100 nm and the pulse width canvary from 100 fs to 10000 fs. The pulse repetition frequency can alsovary from 10 kHz to 250 kHz. Safety limits with regard to unintendeddamage to non-targeted tissue bound the upper limit with regard torepetition rate and pulse energy; while threshold energy, time tocomplete the procedure and stability bound the lower limit for pulseenergy and repetition rate. The peak power of the focused spot in theeye 68 and specifically within the crystalline lens 69 and anteriorcapsule of the eye is sufficient to produce optical breakdown andinitiate a plasma-mediated ablation process. The peak power of the focusspot is also sufficient to treat the vitreous humor, e.g. to treatfloaters or liquify the vitreous humor, as described later. Whentreating the vitreous humor, the laser focus spot may be larger thanwhen treating other parts of the eye, so the peak power will be higherto maintain sufficient peak fluence. Near-infrared wavelengths arepreferred because linear optical absorption and scattering in biologicaltissue is reduced across that spectral range. As an example, laser 4 maybe a repetitively pulsed 1035 nm device that produces 500 fs pulses at arepetition rate of 100 kHz and an individual pulse energy in the tenmicrojoule range. Although not illustrated, UF Light Source 4 may befurther configured to provide higher energy pulses with the same orlonger pulse durations than those exiting the system after pulsecompression. That is, the un-compressed beam may be extracted from UFLight Source 4 in order to provide those higher energy pulses.Regardless, the following system description details means to achievethe usage of higher and/or lower energy pulses.

The laser 4 is controlled by control electronics 300, via an input andoutput device 302, to create optical beam 6. Control electronics 300 maybe a computer, microcontroller, etc. In this example, the entire systemis controlled by the controller 300, and data moved through input/outputdevice IO 302. A graphical user interface GUI 304 may be used to setsystem operating parameters, process user input (UI) 306 on the GUI 304,and display gathered information such as images of ocular structures.

The generated UF light beam 6 proceeds towards the patient eye 68passing through half-wave plate, 8, and linear polarizer, 10. Thepolarization state of the beam can be adjusted so that the desiredamount of light passes through half-wave plate 8 and linear polarizer10, which together act as a variable attenuator for the UF beam 6.Additionally, the orientation of linear polarizer 10 determines theincident polarization state incident upon beamcombiner 34, therebyoptimizing beamcombiner throughput.

The UF beam proceeds through a shutter 12, aperture 14, and a pickoffdevice 16. The system controlled shutter 12 ensures on/off control ofthe laser for procedural and safety reasons. The aperture sets an outeruseful diameter for the laser beam and the pickoff monitors the outputof the useful beam. The pickoff device 16 includes of a partiallyreflecting mirror 20 and a detector 18. Pulse energy, average power, ora combination may be measured using detector 18. The information can beused for feedback to the half-wave plate 8 for attenuation and to verifywhether the shutter 12 is open or closed. In addition, the shutter 12may have position sensors to provide a redundant state detection.

The beam passes through a beam conditioning stage 22, in which beamparameters such as beam diameter, divergence, circularity, andastigmatism can be modified. In this illustrative example, the beamconditioning stage 22 includes a 2 element beam expanding telescopecomprised of spherical optics 24 and 26 in order to achieve the intendedbeam size and collimation. Although not illustrated here, an anamorphicor other optical system can be used to achieve the desired beamparameters. The factors used to determine these beam parameters includethe output beam parameters of the laser, the overall magnification ofthe system, and the desired numerical aperture (NA) at the treatmentlocation. In addition, the optical system 22 can be used to imageaperture 14 to a desired location (e.g. the center location between the2-axis scanning device 50 described below). In this way, the amount oflight that makes it through the aperture 14 is assured to make itthrough the scanning system. Pickoff device 16 is then a reliablemeasure of the usable light.

After exiting conditioning stage 22, beam 6 reflects off of fold mirrors28, 30, & 32. These mirrors can be adjustable for alignment purposes.The beam 6 is then incident upon beam combiner 34. Beamcombiner 34reflects the UF beam 6 (and transmits both the OCT 114 and aim 202 beamsdescribed below). For efficient beamcombiner operation, the angle ofincidence is preferably kept below 45 degrees and the polarization wherepossible of the beams is fixed. For the UF beam 6, the orientation oflinear polarizer 10 provides fixed polarization.

Following the beam combiner 34, the beam 6 continues onto the z-adjustor Z scan device 40. In this illustrative example the z-adjust includesa Galilean telescope with two lens groups 42 and 44 (each lens groupincludes one or more lenses). Lens group 42 moves along the z-axis aboutthe collimation position of the telescope. In this way, the focusposition of the spot in the patient's eye 68 moves along the z-axis asindicated. In general there is a fixed linear relationship between themotion of lens 42 and the motion of the focus. In this case, thez-adjust telescope has an approximate 2× beam expansion ratio and a 1:1relationship of the movement of lens 42 to the movement of the focus.Alternatively, lens group 44 could be moved along the z-axis to actuatethe z-adjust, and scan. The z-adjust is the z-scan device for treatmentin the eye 68. It can be controlled automatically and dynamically by thesystem and selected to be independent or to interplay with the X-Y scandevice described next. Mirrors 36 and 38 can be used for aligning theoptical axis with the axis of z-adjust device 40.

After passing through the z-adjust device 40, the beam 6 is directed tothe x-y scan device by mirrors 46 & 48. Mirrors 46 & 48 can beadjustable for alignment purposes. X-Y scanning is achieved by thescanning device 50 preferably using two mirrors 52 & 54 under thecontrol of control electronics 300, which rotate in orthogonaldirections using motors, galvanometers, or any other well known opticmoving device. Mirrors 52 & 54 are located near the telecentric positionof the objective lens 58 and contact lens 66 combination describedbelow. Tilting these mirrors 52/54 causes them to deflect beam 6,causing lateral displacements in the plane of UF focus located in thepatient's eye 68. Objective lens 58 may be a complex multi-element lenselement, as shown, and represented by lenses 60, 62, and 64. Thecomplexity of the lens 58 will be dictated by the scan field size, thefocused spot size, the available working distance on both the proximaland distal sides of objective 58, as well as the amount of aberrationcontrol. An f-theta lens 58 of focal length 60 mm generating a spot sizeof 10 over a field of 10 mm, with an input beam size of 15 mm diameteris an example. Alternatively, X-Y scanning by scanner 50 may be achievedby using one or more moveable optical elements (e.g. lenses, gratings)which also may be controlled by control electronics 300, via input andoutput device 302.

The aiming and treatment scan patterns can be automatically generated bythe scanner 50 under the control of controller 300. Such patterns may becomprised of a single spot of light, multiple spots of light, acontinuous pattern of light, multiple continuous patterns of light,and/or any combination of these. In addition, the aiming pattern (usingaim beam 202 described below) need not be identical to the treatmentpattern (using light beam 6), but preferably at least defines itsboundaries in order to assure that the treatment light is delivered onlywithin the desired target area for patient safety. This may be done, forexample, by having the aiming pattern provide an outline of the intendedtreatment pattern. This way the spatial extent of the treatment patternmay be made known to the user, if not the exact locations of theindividual spots themselves, and the scanning thus optimized for speed,efficiency and accuracy. The aiming pattern may also be made to beperceived as blinking in order to further enhance its visibility to theuser.

An optional contact lens 66, which can be any suitable ophthalmic lens,can be used to help further focus the optical beam 6 into the patient'seye 68 while helping to stabilize eye position. The positioning andcharacter of optical beam 6 and/or the scan pattern the beam 6 forms onthe eye 68 may be further controlled by use of an input device such as ajoystick, or any other appropriate user input device (e.g. GUI 304) toposition the patient and/or the optical system.

The UF laser 4 and controller 300 can be set to target the surfaces ofthe targeted structures in the eye 68 and ensure that the beam 6 will befocused where appropriate and not unintentionally damage non-targetedtissue. Imaging modalities and techniques described herein, such as forexample, Optical Coherence Tomography (OCT), Purkinje imaging,Scheimpflug imaging, or ultrasound may be used to determine the locationand measure the thickness of the lens and lens capsule to providegreater precision to the laser focusing methods, including 2D and 3Dpatterning. Laser focusing may also be accomplished using one or moremethods including direct observation of an aiming beam, OpticalCoherence Tomography (OCT), Purkinje imaging, Scheimpflug imaging,ultrasound, or other known ophthalmic or medical imaging modalitiesand/or combinations thereof. In the embodiment of FIG. 1, an OCT device100 is described, although other modalities are within the scope of thepresent invention. An OCT scan of the eye will provide information aboutthe axial location of the anterior and posterior lens capsule, theboundaries of the cataract nucleus, as well as the depth of the anteriorchamber. This information is then loaded into the control electronics300, and used to program and control the subsequent laser-assistedsurgical procedure. The information may also be used to determine a widevariety of parameters related to the procedure such as, for example, theupper and lower axial limits of the focal planes used for cutting thelens capsule and segmentation of the lens cortex and nucleus, and thethickness of the lens capsule among others.

The OCT device 100 in FIG. 1 includes a broadband or a swept lightsource 102 that is split by a fiber coupler 104 into a reference arm 106and a sample arm 110. The reference arm 106 includes a module 108containing a reference reflection along with suitable dispersion andpath length compensation. The sample arm 110 of the OCT device 100 hasan output connector 112 that serves as an interface to the rest of theUF laser system. The return signals from both the reference and samplearms 106, 110 are then directed by coupler 104 to a detection device128, which employs either time domain, frequency or single pointdetection techniques. In FIG. 1, a frequency domain technique is usedwith an OCT wavelength of 920 nm and bandwidth of 100 nm.

Exiting connector 112, the OCT beam 114 is collimated using lens 116.The size of the collimated beam 114 is determined by the focal length oflens 116. The size of the beam 114 is dictated by the desired NA at thefocus in the eye and the magnification of the beam train leading to theeye 68. Generally, OCT beam 114 does not require as high an NA as the UFbeam 6 in the focal plane and therefore the OCT beam 114 is smaller indiameter than the UF beam 6 at the beamcombiner 34 location. Followingcollimating lens 116 is aperture 118 which further modifies theresultant NA of the OCT beam 114 at the eye. The diameter of aperture118 is chosen to optimize OCT light incident on the target tissue andthe strength of the return signal. Polarization control element 120,which may be active or dynamic, is used to compensate for polarizationstate changes which may be induced by individual differences in cornealbirefringence, for example. Mirrors 122 & 124 are then used to directthe OCT beam 114 towards beamcombiners 126 & 34. Mirrors 122 & 124 maybe adjustable for alignment purposes and in particular for overlaying ofOCT beam 114 to UF beam 6 subsequent to beamcombiner 34. Similarly,beamcombiner 126 is used to combine the OCT beam 114 with the aim beam202 described below.

Once combined with the UF beam 6 subsequent to beamcombiner 34, OCT beam114 follows the same path as UF beam 6 through the rest of the system.In this way, OCT beam 114 is indicative of the location of UF beam 6.OCT beam 114 passes through the z-scan 40 and x-y scan 50 devices thenthe objective lens 58, contact lens 66 and on into the eye 68.Reflections and scatter off of structures within the eye provide returnbeams that retrace back through the optical system, into connector 112,through coupler 104, and to OCT detector 128. These return backreflections provide the OCT signals that are in turn interpreted by thesystem as to the location in X, Y Z of UF beam 6 focal location.

OCT device 100 works on the principle of measuring differences inoptical path length between its reference and sample arms. Therefore,passing the OCT through z-adjust 40 does not extend the z-range of OCTsystem 100 because the optical path length does not change as a functionof movement of 42. OCT system 100 has an inherent z-range that isrelated to the detection scheme, and in the case of frequency domaindetection it is specifically related to the spectrometer and thelocation of the reference arm 106. In the case of OCT system 100 used inFIG. 1, the z-range is approximately 1-2 mm in an aqueous environment.Extending this range to at least 4 mm involves the adjustment of thepath length of the reference arm within OCT system 100. Passing the OCTbeam 114 in the sample arm through the z-scan of z-adjust 40 allows foroptimization of the OCT signal strength. This is accomplished byfocusing the OCT beam 114 onto the targeted structure whileaccommodating the extended optical path length by commensuratelyincreasing the path within the reference arm 106 of OCT system 100.

Because of the fundamental differences in the OCT measurement withrespect to the UF focus device due to influences such as immersionindex, refraction, and aberration, both chromatic and monochromatic,care must be taken in analyzing the OCT signal with respect to the UFbeam focal location. A calibration or registration procedure as afunction of X, Y Z should be conducted in order to match the OCT signalinformation to the UF focus location and also to the relate to absolutedimensional quantities.

Observation of an aim beam may also be used to assist the user todirecting the UF laser focus. Additionally, an aim beam visible to theunaided eye in lieu of the infrared OCT and UF beams can be helpful withalignment provided the aim beam accurately represents the infrared beamparameters. An aim subsystem 200 is employed in the configuration shownin FIG. 1. The aim beam 202 is generated by an aim beam light source201, such as a helium-neon laser operating at a wavelength of 633 nm.Alternatively a laser diode in the 630-650 nm range could be used. Theadvantage of using the helium neon 633 nm beam is its long coherencelength, which would enable the use of the aim path as a laser unequalpath interferometer (LUPI) to measure the optical quality of the beamtrain, for example.

Once the aim beam light source generates aim beam 202, the aim beam 202is collimated using lens 204. The size of the collimated beam isdetermined by the focal length of lens 204. The size of the aim beam 202is dictated by the desired NA at the focus in the eye and themagnification of the beam train leading to the eye 68. Generally, aimbeam 202 should have close to the same NA as UF beam 6 in the focalplane and therefore aim beam 202 is of similar diameter to the UF beamat the beamcombiner 34 location. Because the aim beam is meant tostand-in for the UF beam 6 during system alignment to the target tissueof the eye, much of the aim path mimics the UF path as describedpreviously. The aim beam 202 proceeds through a half-wave plate 206 andlinear polarizer 208. The polarization state of the aim beam 202 can beadjusted so that the desired amount of light passes through polarizer208. Elements 206 & 208 therefore act as a variable attenuator for theaim beam 202. Additionally, the orientation of polarizer 208 determinesthe incident polarization state incident upon beamcombiners 126 and 34,thereby fixing the polarization state and allowing for optimization ofthe beamcombiners' throughput. Of course, if a semiconductor laser isused as aim beam light source 200, the drive current can be varied toadjust the optical power.

The aim beam 202 proceeds through a shutter 210 and aperture 212. Thesystem controlled shutter 210 provides on/off control of the aim beam202. The aperture 212 sets an outer useful diameter for the aim beam 202and can be adjusted appropriately. A calibration procedure measuring theoutput of the aim beam 202 at the eye can be used to set the attenuationof aim beam 202 via control of polarizer 206.

A device for imaging the target tissue on or within the eye 68 is shownschematically in FIG. 1 as imaging system 71. Imaging system includes acamera 74 and an illumination light source 86 for creating an image ofthe target tissue. The imaging system 71 gathers images which may beused by the system controller 300 for providing pattern centering aboutor within a predefined structure. The illumination light source 86 forthe viewing is generally broadband and incoherent. For example, lightsource 86 can include multiple LEDs as shown. The wavelength of theviewing light source 86 is preferably in the range of 700 nm to 750 nm,but can be anything that is accommodated by the beamcombiner 56, whichcombines the viewing light with the beam path for UF beam 6 and aim beam202 (beamcombiner 56 reflects the viewing wavelengths while transmittingthe OCT and UF wavelengths). The beamcombiner 56 may partially transmitthe aim wavelength so that the aim beam 202 can be visible to theviewing camera 74. Optional polarization element 84 in front of lightsource 86 can be a linear polarizer, a quarter wave plate, a half-waveplate or any combination, and is used to optimize signal. A false colorimage as generated by the near infrared wavelength is acceptable.

The illumination light from light source 86 is directed down towards theeye using the same objective lens 58 and contact lens 66 as the UF andaim beam 6, 202. The light reflected and scattered off of variousstructures in the eye 68 are collected by the same lenses 58 & 66 anddirected back towards beamcombiner 56. There, the return light isdirected back into the viewing path via beam combiner and mirror 82, andon to camera 74. Camera 74 can be, for example but not limited to, anysilicon based detector array of the appropriately sized format. Videolens 76 forms an image onto the camera's detector array while opticalelements 80 & 78 provide polarization control and wavelength filteringrespectively. Aperture or iris 81 provides control of imaging NA andtherefore depth of focus and depth of field. A small aperture providesthe advantage of large depth of field which aids in the patient dockingprocedure. Alternatively, the illumination and camera paths can beswitched. Furthermore, aim light source 200 can be made to emit in theinfrared which would not directly visible, but could be captured anddisplayed using imaging system 71.

Coarse adjust registration is usually needed so that when the contactlens 66 comes into contact with the cornea, the targeted structures arein the capture range of the X, Y scan of the system. Therefore a dockingprocedure is preferred, which preferably takes in account patient motionas the system approaches the contact condition (i.e. contact between thepatient's eye 68 and the contact lens 66. The viewing system 71 isconfigured so that the depth of focus is large enough such that thepatient's eye 68 and other salient features may be seen before thecontact lens 66 makes contact with eye 68.

An alternative beamcombining configuration is shown in the alternateembodiment of FIG. 2. For example, the passive beamcombiner 34 in FIG. 1can be replaced with an active combiner 140 in FIG. 2. The activebeamcombiner 34 can be a moving or dynamically controlled element suchas a galvanometric scanning mirror, as shown. Active combiner 140changes it angular orientation in order to direct either the UF beam 6or the combined aim and OCT beams 202,114 towards the scanner 50 andeventually eye 68 one at a time. The advantage of the active combiningtechnique is that it avoids the difficulty of combining beams withsimilar wavelength ranges or polarization states using a passive beamcombiner. This ability is traded off against the ability to havesimultaneous beams in time and potentially less accuracy and precisiondue to positional tolerances of active beam combiner 140.

Another alternate embodiment is shown in FIG. 3 which is similar to thatof FIG. 1 but utilizes an alternate approach to OCT 100. In FIG. 3, OCT101 is the same as OCT 100 in FIG. 1, except that the reference arm 106has been replaced by reference arm 132. This free-space OCT referencearm 132 is realized by including beamsplitter 130 after lens 116. Thereference beam 132 then proceeds through polarization controllingelement 134 and then onto the reference return module 136. The referencereturn module 136 contains the appropriate dispersion and path lengthadjusting and compensating elements and generates an appropriatereference signal for interference with the sample signal. The sample armof OCT 101 now originates subsequent to beamsplitter 130. The potentialadvantages of this free space configuration include separatepolarization control and maintenance of the reference and sample arms.The fiber based beam splitter 104 of OCT 101 can also be replaced by afiber based circulator. Alternately, both OCT detector 128 andbeamsplitter 130 might be moved together as opposed to reference arm136.

FIG. 4 shows another alternative embodiment for combining OCT beam 114and UF beam 6. In FIG. 4, OCT 156 (which can include either of theconfigurations of OCT 100 or 101) is configured such that its OCT beam154 is coupled to UF beam 6 after the z-scan 40 using beamcombiner 152.In this way, OCT beam 154 avoids using the z-adjust. This allows the OCT156 to possibly be folded into the beam more easily and shortening thepath length for more stable operation. This OCT configuration is at theexpense of an optimized signal return strength as discussed with respectto FIG. 1. There are many possibilities for the configuration of the OCTinterferometer, including time and frequency domain approaches, singleand dual beam methods, swept source, etc., as described in U.S. Pat.Nos. 5,748,898; 5,748,352; 5,459,570; 6,111,645; and 6,053,613 (whichare incorporated herein by reference.)

The device according to FIGS. 1-4 is suitable for scanning 3-dimensionalpatterns within lens 69 and cornea of the patient's eye 68 as describedin U.S. Pat. No. 9,278,028, the entirety of which is incorporated byreference in its entirety. Suitable patterns may be scanned using thelaser to provide convenient splitting of lens 69 into segments that areeasy to aspirate using existing technology and devices.Phacoemulsification is particularly well suited for this. Several suchaspiration devices are commercially available and well known in the art.

Full Depth Laser Ophthalmic Surgical System Using a Focal PointExtension Assembly.

A first aspect of the present invention is directed to a Full DepthLaser Ophthalmic Surgical System. Most prior ophthalmic surgical systemsare capable of only being used for a portion of the eye. These includethe system described in detail later with reference to FIGS. 1-4(referred to hereinafter as “the existing laser ophthalmic surgicalsystem”), which, when used with a corresponding patient interface devicehaving a lens with a predefined optical power, can focus the laser beamin the region of the eye from the cornea to about the location of thelens posterior in the patient. Traditionally, other surgical systems, orcold steel methods, would be required for surgical interventions on theeye that were posterior to the lens, such as surgical interventions inthe vitreous humor or the retina. According to an embodiment of thepresent invention, a removeable lens assembly has been made which extendthe focal point of the existing laser ophthalmic surgical system so thatthe focal point of the laser system can be extended to portions of theeye posterior to the lens. This “focal point extension assembly” extendsthe focal point of the existing laser ophthalmic surgical system so thatit can reach the vitreous humor and the retina. Thus, the existing laserophthalmic surgical system coupled with the removeable focal pointextension assembly create a “full depth” ophthalmic surgical systemcapable of performing surgical procedures along the entire length of theeye.

FIGS. 5A and 5B illustrate an example of a modified patient interfacethat incorporates a focal point extension assembly, which is configuredto extend the focal zone of the existing laser ophthalmic surgicalsystem so that the focal zone can extend into the portions of the eyeposterior to the lens capsule. The modified patient interfaceconstitutes a removable focal zone extension adapter. The patientinterface has a structure otherwise similar to an existing patientinterface, such as that described in U.S. Pat. Appl. Pub. No.2013/0102922, published Apr. 25, 2013 (the content of which isincorporated herein by reference in its entirety), but includes anoptical assembly (an adapter lens) that provides a less positive or morenegative optical power (as compared to the patient interface that isused with the same existing laser ophthalmic surgical system whentreating the lens of the eye) to lengthen the focus. In the embodimentshown in FIG. 5B, the optical assembly is a doublet, i.e. two lensesjoined together, without any air gap in between. This optical elementprovides better optical property and correspondingly better beam qualitythan a single lens. In addition, the optical assembly is optimized toachieve a reasonable beam quality over a reasonable field such assubstantially the entire distance between the retina and the posteriorlens capsule. In the embodiment shown in FIG. 5B, the upper end of themodified patient interface is configured to be attached to the objectivelens assembly of the laser beam delivery system, and the lower end ofthe patient interface has a suction ring configured to engage thepatient's eye via a vacuum force. The structures of the upper and lowerends of the patient interface are similar to those in the above-citedpatent.

Note that the modified patient interface having the focal pointextension assembly extends the focus distances of both the treatmentlaser and the imaging system beam, as well as that of the aim beam. Acalibration or registration procedure as a function of X, Y Z should beconducted using the modified patient interface in order to match the OCTsignal information to the treatment later focus location and also to therelate to absolute dimensional quantities. As described earlier, acalibration or registration procedure is conducted for the existingpatient interface. The resulting calibration parameters for bothcalibrations, for example, in the form of different lookup tables, arestored in the controller.

Thus, when using the existing laser ophthalmic surgical system toperform surgical procedures in the vitreous humor of the eye, themodified patient interface having the focal point extension opticalassembly is used, along with the corresponding calibration parameters;when using the same existing laser ophthalmic surgical system to performsurgical procedures in the anterior portions of the eye such as thecornea, the lens capsule and the lens, such as for cataract surgery, theexisting patient interface without the focal point extension opticalassembly is used, along with the corresponding calibration parameters.This allows the same laser system to be used to treat the full range oflocations of the eye.

Full Depth Laser Ophthalmic Surgical System Optimized for Treating theVitreous.

In an alternative embodiment of this aspect of the invention, theoptical system is configured to scan the laser beam and the imaging beam(e.g., the OCT light) in the Z (depth) direction within the full rangeof the eye, from the cornea to the retina; the optical parameters (suchas the NA and the Strehl ratio) are optimized for scanning the laserbeam and the imaging beam in the entire vitreous volume. FIG. 6schematically illustrates an example of such an optical system. As shownin FIG. 6, the laser beam and the imaging beam, having been directedinto the same optical path by a beam combiner (not shown in FIG. 6),passes through a Z-scanner, which includes a lens L1 COM that ismoveable along the optical axis. In a preferred embodiment, the lens L1COM is a negative spherical lens having an effective focal length (EFL)of −39.90 mm and a back focal length (BFL) of −40.98 mm (for 632.8 nmlight). The laser beam and the imaging beam then pass through anotherlens L2 COM, and are aligned by two folding mirrors M3 COM and M4 COMand delivered to the XY-scanner which comprises two scanning mirrors GXand GY. The laser beam and imaging beam output from the XY-scanner aretransmitted through a beam splitter BC3, and then focused by anobjective lens OBJ. The reflected OCT light from the eye travels in theopposite direction through the objective lens OBJ, the beam splitterBC3, and the scanner back to the OCT assembly for detection.

In a preferred embodiment, the objective lens OBJ is a lens groupincluding five lenses OBJ-1 to OBJ-5, with lenses OBJ-1 to OBJ-4 beingdoublet lenses and the downstream-most lens OBJ-5 being a meniscus lens.Each of OBJ-1 and OBJ-2 has a focal length of 100 mm and each of OBJ-3and OBJ-4 has a focal length of 150 mm, and the meniscus lens OBJ-5 hasan EFL of 616.97 mm and a BFL of 744.43 mm (for 632.8 nm light).

The optical system is intended to be used with patient interface coupledto the downstream end of the objective lens group OBJ during ophthalmicprocedures. The patient interface includes a focusing lens WCL. In apreferred embodiment, the focusing lens is plano-convex having aspherical surface at the proximate end (closer to the objective lens)and a flat surface at the distal end (closer to the eye), with an EFL of30.06 mm and a BFL of 24.87 mm (for 632.8 nm light). The parameters ofthe meniscus lens OBJ-5 described in the preceding paragraph areoptimized for a patient interface having the plano-convex focusing lensWCL described above. In an alternative embodiment, the focusing lens WCLof the patient interface is a double convex lens, and has a convexsurface at the distal end. The convex surface facing the eye can helpreduce bubbles in the fluid between the focusing lens WCL and thesurface of the eye. In such an embodiment, the parameters of themeniscus lens OBJ-5 will be modified accordingly to optimize it for thedouble convex lens WCL. The doublet lenses and the meniscus lens of theobjective lens group OBJ, together with the lens WCL of the patientinterface, deliver the focal spots of the laser beam and the imagingbeam to the vitreous volume with minimal aberrations.

The optical system is also configured to direct a fixation light and anillumination light to the eye and direct light reflected or otherwiseemitted from the eye back to a video camera for imaging. The fixationlight from a fixation light source is collimated by a lens L-FIX, thenreflected by a beam splitter Fixation BS to the beam splitter BC3, whichin turn reflects the fixation light to the objective lens OBJ. Theillumination light, emitted by an LED illumination ring, is transmittedthrough the beam splitter Fixation BS and then reflected by the beamsplitter BC3 to the objective lens OBJ. The objective lens OBJ focusesthe fixation light and the illumination light into the eye. An importantfeature of the camera illumination light source placement andconfiguration is that it can be pupil matched to the pupil of thepatient's eye in a manner similar to locating the image of the X & Yscan mirrors near the pupil (described later). That is, the objectivelens group OBJ and the focusing lens of WCL of the patient interfacepreferably form an image of the illumination source ear the pupil of thepatient's eye, and substantially centered with the fixation light, asare images of the X & Y scan mirrors. This configuration allows forillumination of a larger field in the full depth range of the eye. Thelight reflected or otherwise emitted from the eye travels backwardsthrough the objective lens OBJ and is reflected by the beam splitterBC3. After transmitting through the beam splitter Fixation BS, the lightfrom the eye passes through an aperture AS VIEW and is focused byadditional lenses, including a tunable lens and three doublet lenses L1VIEW to L3 VIEW in a preferred embodiment, onto the camera detector CAMwhich generates an image of the eye. The tunable lens can be eithertunable by moving the lens, or by adjusting the optical power of thelens.

The Z scanner (L1 COM), the XY scanner (GX and GY), and the tunable lensfor the video camera CAM are electrically coupled to the controller ofthe laser ophthalmic surgical system, and controlled by the controllerto scan of the laser beam and the imaging beam (e.g. the OCT beam)within the eye and to image the eye with the video camera.

This optical system is optimized to focus and scan the laser beam andthe imaging beam in substantially the entire depth of vitreous humor ofthe eye from the posterior lens capsule to the retina. In actualsurgery, it is desired to maintain safe zones (i.e. zones free of laserfocal spot scanning) of a depth of about 4 mm after the lens (theposterior lens capsule) and a depth of about 3 mm before the retina.FIG. 7 schematically illustrates the focusing of the laser beam and theimaging beam in a depth range between the two safe zones, with a viewingangle of 45 degrees for the X scan and 38 degrees for the Y scan. Itshould be noted that the light exiting the focusing lens WCL of thepatient interface is further refracted by the optical elements of theeye, including the cornea and the lens of the eye (it should be noted,however, that due to the fluid bath in the patient interface thatcontacts the cornea, focusing by the cornea tends to be minimal); theoptical system design takes this into consideration. Moreover, when thepatient interface is one where the distal surface of the focusing lensWCL does not directly contact the cornea of the eye but uses a fluidbath located between the WCL lens and the cornea, the relative distanceof the patient's eye from the WCL lens surface is a function of thedesign of the patient interface such as the size of the fluid chamber.Thus, the optical system is designed such that the focusing range coversthe entire desirable range within the eye after taking intoconsideration all of the factors discussed above. In one particularexample, the optical system is designed such that without the eye, thefocal spot of the laser beam can be scanned within a depth range of 15mm to 24 mm in water beyond the distal surface of the focusing lens WCLof the patient interface.

As shown in FIG. 7, the optical system focuses the laser beam andimaging beam within the vitreous volume with wide viewing angles in boththe X and Y scanning directions. This is achieved by the objective lensgroup OBJ and the focusing lens of WCL of the patient interface, whichtogether function as relay optics to form respective images of thescanning mirrors GX and GY at locations near or at the pupil plane ofthe eye, as shown in FIG. 7C. In a conventional optical beam scanningsystem that is designed to scan the focal spot of the laser to treat theanterior segments of the eye including the cornea and the lens, asillustrated in FIG. 7A, the depth range of the focal spot is typicallylimited to the lens posterior capsule. When the conventional opticalbeam scanning system is used with a different patient interface lensthat extends the depth range of the laser focal spot to the vitreous andthe retina, as shown in FIG. 7B, due to the fact that in suchconventional optical beam scanning system the pivot points of thescanning mirrors GX and GY are located far away from the pupil of theeye, the pupil diameter limits the transverse scanning range of thebeam. In this situation, the volume that can be reached by the laserfocal spot is approximately a tapered cylinder that has a maximumdiameter less than the pupil diameter. In embodiments of the presentinvention, as shown in FIG. 7C, due to the relay optics, the scannedlaser beam emanates from the locations of the images of the scanningmirrors GX and GY, which are located near or at the pupil plane of theeye. This makes the scanning angle in the eye much wider, and the beamcan reach a volume in the vitreous that has a maximum diameter largerthan the pupil diameter. In a preferred embodiment, the images of thescanner mirrors are located about 0 to 5 mm from the patient's irisplane. When the system is used with a patient interface that employs afluid bath between the cornea and the distal surface of the focusinglens WCL of the patient interface, the optical design takes into accountthe approximate distance between the WCL lens surface and the cornea inorder to form the images of the scanner mirrors at the above-describeddesired location relative to the patient's iris plane. In one particularexample, the optical system is designed such that the images of thescanner mirrors are located about 0 to 10 mm from the distal surface ofthe focusing lens WCL of the patient interface. It should be noted thatthe same considerations apply to the design of the optical system toform an image of the illumination light source near the iris plane asdiscussed earlier. In operation, the depth location of the iris from thedistal surface of the focusing lens of the patient interface may bemeasured, and the objective lens is controlled to form the image of thescanning mirrors, as well as the illumination light as mentionedearlier, at the pupil.

By using the tunable lens before the video camera, the optical system isconfigured to focus light emitted anywhere within the entire depth ofthe eye onto the video camera CAM, so as to image different planes ofthe eye from the iris to the retina. Again, the light emitted from thevitreous of the eye will be refracted by optical elements of the eyesuch as the lens (and to a much lesser extent the cornea), and thedesign of the optical system takes this into consideration. Without theeye, the optical system can image objects within a depth range of 8 mmto 29 mm in water beyond the distal surface of the focusing lens WCL ofthe patient interface. In a preferred embodiment, the tunable lens has atunable range of −10D to +10D. As mentioned earlier, the tunable lenscan be either tunable by adjusting the optical power of the lens, or bymoving an imaging lens having a fixed optical power. Such a fixed powerlens may be mounted on a mechanically moveable stage (moved by a motoror an actuator), and the movement of the stage is controlled by thecontroller to change the imaging location of the video camera. Themovement range of the stage is configured to allow the video camera toimage different planes of the eye from the iris to the retina.

The illumination light source is ring shaped, and located near theaperture AS VIEW of the video camera and coaxially with the optical axisof the video camera. This configuration allows the illumination light toilluminate a wide field and the entire depth range from the iris to theretina to aid camera imaging.

While the optical system of this alternative embodiment is described inconsiderable detail, variations of the optical design are also withinthe scope of the invention, so long as they can scan the laser beam andthe imaging beam to the desired depth range within the eye, direct theillumination light to a wide field and the entire depth range of theeye, and focus the light emitted from the entire depth range eye to thevideo camera. For example, different combinations of imaging lenses toreach the same or different F numbers or magnifications may be used.

Systems and Methods for Calibrating the Ophthalmic Surgical Systems forProcedures Performed Posterior to the Lens.

A problem associated with using laser systems, such as that according toFIGS. 1-4 in the posterior portion of the eye is that it is verydifficult to properly calibrate the surgical system for use in theposterior portion. This is due to the fact that there is an unknownoptical element, i.e. the patient's lens (with an unknown refractivepower), between the laser source and location of the focal zone in thepatient's eye. As a result of this unknown optical element, there can bea significant difference between the apparent location of the focal zoneand the actual location of the focal zone. This can be dangerous as thefocal zone could unknowingly be in dangerous location. While usingaverage values for eye physiology may be satisfactory for much of thepopulation, there could be a significant risk for persons whose eyes areoutside normal physiological averages. One method is to use structuraldata of the lens of the patient's eye, obtained using the OCT system, todetermine the individual active optical power of the lens, in order toaccurately place the laser focus within the vitreous volume.Alternatively, fast and efficient calibration methods can be done foreach individual patient as described below.

One aspect of the present invention is directed to systems and methodsfor calibration of laser surgical systems for use in portions of the eyethat are posterior to the human lens. A system and method for thecalibration is based on the use of the imaging subsystem's opticalcoherence tomographer. In essence, the focal zone of the opticalcoherence tomographer beam is used as a proxy for the focal zone of thefemtosecond laser source. This method may be implemented using eitherthe existing laser ophthalmic surgical system with the modified patientinterface shown in FIG. 5B, or a laser ophthalmic surgical system havingthe optical system shown in FIG. 6.

The method can be summarized by the following steps:

1. Use the OCT to find the relevant structure (i.e. the retina) based onan area of bright return of the OCT beam;

2. Move the focal zone of the OCT beam in the anterior direction by apredetermined distance from the relevant structure identified in step 1(the predetermined distance corresponds to a safety zone, e.g. 2 mm fromthe retina);

3. Set this new location as the safe limiting position of the focal zoneof the laser beam;

4. Repeat for other relevant structures as necessary (i.e. posteriorportion of the lens capsule, in which case the safety limitationposition is a predetermined distance (e.g. 2 mm) in the posteriordirection of the lens posterior capsule)

More specifically, the focal zone of OCT beam is scanned in the depthdirection (using the Z scan device of the laser system) in regions ofthe eye posterior to the posterior lens capsule, and the intensity ofthe returned (i.e. reflected) OCT beam is measured as a function ofdepth. Peaks of the intensity function are identified to determine thedepth location of the retina, the posterior lens capsule, and optionallyother structures of the eye. The safety limiting depths are set based onthe depths of the retina and posterior lens capsule, e.g., at 2 mmanterior of the retina and 2 mm posterior of the posterior lens capsule.Note that this safety distance is a function of pulse energy. Otherappropriate safety values may be determined based on experiments. Theparameters of the Z scan device that correspond to these various depthsare determined, which can then be used by the controller to scan thefocal zone of the treatment laser beam for treating the vitreous humor,e.g. to treat floaters or liquify the vitreous humor as describedherein. The scan of the treatment beam is performed within the volumebound by the safety limitation positions described above. This methodallows one to safely set the location of the laser beam taking intoaccount the individual refractive power of each person's eye and at thesame time allows one to identify a safe surgical zone for the ophthalmicsurgery in portions of the eye posterior to the lens.

Treatment Methods and Systems Carrying Out the Method: Liquification ofthe Vitreous Humor.

Surgical procedures sometimes require removal of the vitreous. However,this can be difficult because of the gelatin like structure of thevitreous. In addition, the vitreous may be adhered to various delicatestructures of the eye (e.g. the retina) and it can be difficult toremove the vitreous without disturbing other structures. An in vitrostudy in rabbits performed by the instant inventors showed theliquification of the vitreous humor with the femtosecond laser surgicalsystem described above can be performed safely. Liquification of thevitreous may be indicated in surgical procedures where removal of thevitreous is required.

To liquify the vitreous humor, either the existing laser ophthalmicsurgical system with the modified patient interface shown in FIG. 5B, ora laser ophthalmic surgical system having the optical system shown inFIG. 6, is used. The retina and the lens posterior capsule are located,for example using the process described above. The imaging system suchas the OCT system may be used to image the structure of the vitreoushumor to identify the outer boundaries for liquification. The outerboundaries may be determined by the human operator or by the controllerbased on the images. A treatment plan can then be defined with theassistance of the controller. For example, a scan pattern of the laserfocal spot within the volume defined by the boundaries can be programmedusing the controller. The treatment plan is then executed to scan thefocal spot of the laser beam according to the scan pattern, to therebyperform a volumetric treatment of the vitreous humor to enableliquification. The following laser beam parameters may be used inpreferred embodiments: Wavelength: preferably 1000-1100 nm, and morepreferably 1030 nm; pulse width: preferably 100-1000 fs, and morepreferably 100-600 fs; pulse energy: preferably 2-20 μJ; repetitionrate: preferably 1-500 kHz; total energy: preferably less than 40 J. Inan animal test using rabbit eyes, the following laser parameters wereused to successfully liquify the vitreous humor: Wavelength: 1030 nm;pulse width: about 400 fs; pulse energy: about 9 μJ; repetition rate:6-24 kHz; total energy: 10-40 J.

Treatment Methods and Systems Carrying Out the Method: Treatment ofFloaters and Other Vitreous Treatment.

In addition to vitreous liquification, either the existing laserophthalmic surgical system with the modified patient interface shown inFIG. 5B, or a laser ophthalmic surgical system having the optical systemshown in FIG. 6, may be used to treat vitreous floaters. The OCT and/orthe video camera system may be used to locate the vitreous floaters, andtreatment plan is determined and executed to specifically target thefloaters for treatment. For example, the laser focal spot may be scannedin a volume that includes the floaters to destroy or remove thefloaters. Further, the system may be used to pre-treat the vitreousvolume before vitrectomy to simplify the surgical procedure and reducepossible complications.

In this disclosure, as is customary in the field of ophthalmic surgery,the term “depth” refers to a direction of the eye that extends fromcornea to the retina; it corresponds to the Z direction of the laserophthalmic surgical system as described above. The terms “anterior” and“posterior” are relative terms and refer to locations closer to thecornea and closer to the retina, respectively.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

While certain illustrated embodiments of this disclosure have been shownand described in an exemplary form with a certain degree ofparticularity, those skilled in the art will understand that theembodiments are provided by way of example only, and that variousvariations can be made without departing from the spirit or scope of theinvention. Thus, it is intended that this disclosure cover allmodifications, alternative constructions, changes, substitutions,variations, as well as the combinations and arrangements of parts,structures, and steps that come within the spirit and scope of theinvention as generally expressed by the following claims and theirequivalents.

1. A full depth ophthalmic surgical system for performing surgery oneyes of subjects, comprising: a femtosecond laser source configured toproduce a pulsed laser beam; an imaging assembly comprising an opticalcoherence tomographer; a scanning assembly for deflecting the laserbeam; a first patient interface device configured to engage an eye of asubject and configured to be removably connected to the scanningassembly, the first patient interface device having a first predefinedoptical power; a second patient interface device configured to engage aneye of a subject and configured to be removably connected to thescanning assembly, the second patient interface device having a secondpredefined optical power which is less positive or more negative thanthe first predefined optical power, the first patient interface and thesecond patient interface being alternatively connected to the scanningassembly; and a controller operably connected to the laser source, theimaging assembly and the scanning assembly and programmed to: operatethe optical coherence tomographer to scan an imaging beam in a first eyein a first region including a lens of the first eye and structuresanterior to the lens when the first patient interface is engaged withthe first eye and connected to the scanning assembly, thereby obtainingimage information corresponding to the first region of the first eye;operate the scanning assembly to scan a focal spot of the laser beam inthe first region of the first eye to treat a tissue in the first regionwhen the first patient interface is engaged with the first eye andconnected to the scanning assembly; operate the optical coherencetomographer to scan an imaging beam in a second eye in a second regionincluding structures posterior to a lens of the second eye when thesecond patient interface is engaged with the second eye and connected tothe scanning assembly, thereby obtaining image information correspondingto the second region of the second eye; and operate the scanningassembly to scan a focal spot of the laser beam in the second region ofthe second eye to treat a tissue in the second region when the secondpatient interface is engaged with the second eye and connected to thescanning assembly.
 2. The system of claim 1, wherein each of the firstand the second patient interface device comprises: a body having anupper end and a lower end; wherein the upper end is configured to beremovably attached to an objective lens assembly of the ophthalmicsurgical system; a flexible suction ring disposed at the lower end ofthe body, configured to engage the eye via a vacuum force; and anoptical assembly disposed within the body and having the respectiveoptical power.
 3. The patient interface of claim 2, wherein the opticalassembly of the second patient interface device is a doublet lens.
 4. Afull depth ophthalmic surgical system for performing surgery on an eyeof a subject, comprising: a femtosecond laser source configured toproduce a femtosecond pulsed laser beam; an imaging assembly configuredto emit an imaging beam; a scanning assembly including a Z scanner andan XY scanner, configured to scan a focal spot of the laser beam and theimaging beam within the eye in a depth direction and two transversedirections, respectively; an illumination light source configured toemit an illumination light; a video camera assembly; an objective lensassembly configured to focus the laser beam and the imaging beam; apatient interface configured to be coupled to the objective lensassembly and to engage the eye, the patient interface including a lenshaving a predefined optical power; and optical components including atleast one beam splitter, configured to direct the laser beam and theimaging beam output by the scanning assembly and the illumination lightto the objective lens assembly, and to direct light emitted from withinthe eye, which has passed through the objective lens assembly, to thevideo camera assembly; wherein the scanning assembly, the objective lensassembly and the lens of the patient interface are configured to form afocal spot of the laser beam at any depth within a range of 15 mm to 24mm in water beyond a distal surface of the lens of the patientinterface.
 5. The ophthalmic surgical system of claim 4, wherein theillumination light source is a ring-shaped light source, wherein thevideo camera assembly includes a detector and a tunable lens in front ofthe detector, and wherein the tunable lens of the video camera assemblyis configured to focus light emitted from any distance within a range of8 mm to 29 mm in water beyond the distal surface of the lens of thepatient interface.
 6. The ophthalmic surgical system of claim 5, whereinthe objective lens assembly and the focusing lens of the patientinterface are configured to form an image of the illumination lightsource at locations 0 to 10 mm from a distal surface of the lens of thepatient interface.
 7. The ophthalmic surgical system of claim 4, whereinthe objective lens assembly includes four doublet lenses and a meniscuslens.
 8. The ophthalmic surgical system of claim 4, wherein the imagingassembly comprises an optical coherence tomographer, a Purkinje imagingassembly, or a Scheimpflug imaging assembly.
 9. The ophthalmic surgicalsystem of claim 4, further comprising a fixation light source configuredto generate a fixation light, wherein the optical components are furtherconfigured to direct the fixation light to the objective lens assembly.10. The ophthalmic surgical system of claim 4, wherein the XY scannerincludes two scanning mirrors, and wherein the objective lens assemblyand the lens of the patient interface are configured to form respectiveimages of the two scanning mirrors at locations 0 to 10 mm from a distalsurface of the focusing lens of the patient interface.
 11. Theophthalmic surgical system of claim 4, further comprising a controlleroperably connected the laser source, the imaging assembly, the scanningassembly, and the video camera assembly and programmed to: operate theimaging assembly to form images of structures within a vitreous humor ofthe eye; identify outer boundaries of a treatment volume located in thevitreous humor based on the images; define a scan pattern for scanningthe focal spot of the laser beam within the treatment volume; andoperate the scanning assembly to scan the focal spot of the laser beamin the treatment volume in the vitreous humor according to the scanpattern to liquify the vitreous humor in the treatment volume.
 12. Theophthalmic surgical system of claim 4, further comprising a controlleroperably connected to the laser source, the imaging assembly, thescanning assembly, and the video camera assembly and programmed to:operate the imaging assembly or the video camera assembly to form imagesof structures in a vitreous humor of the eye; identify floaters locatedin the vitreous humor based on the images; define a treatment volumewithin the vitreous humor that includes the identified floaters; definea scan pattern for scanning the focal spot of the laser beam within thetreatment volume; and operate the scanning assembly to scan the focalspot of the laser beam in the treatment volume in the vitreous humoraccording to the scan pattern to destroy or remove the floaters.
 13. Amethod for treating a vitreous humor of an eye of a subject using alaser ophthalmic surgical system, the ophthalmic surgical systemincluding an ultrafast laser system, an optical coherence tomographer,and shared optical components, the method comprising: operating theshared optical components to scan a focal zone of a light beam of theoptical coherence tomographer in a region of the eye posterior to a lensof the eye; detecting an intensity of the light beam after it isreflected from the eye; determining a depth of a retina of the eye basedthe detected intensity of the reflected light beam; setting a first safelimiting depth which is at a predetermined distance from the depth ofthe retina in an anterior direction; determining another depth ofanother structure of the eye based the detected intensity of thereflected light beam; setting a second safe limiting depth which is atanother predetermined distance from the depth of the other structure ina posterior direction; and based on the first and second safe limitingdepths, operating the shared optical components to scan a focal zone ofa laser beam of the ultrafast laser within a volume of the eye betweenthe first safe limiting depth and the second safe limiting depth. 14.The method of claim 13, wherein the other structure of the eye is aposterior lens capsule of the eye.
 15. A method of liquefying a portionof a vitreous humor of an eye, comprising: irradiating at least aportion of the vitreous humor of the eye with a focal spot of a pulsedlaser beam emitted from a laser source, the laser beam comprising laserpulses having a wavelength of 1000-1100 nm, a pulse width of 100-1000fs, a pulse energy of 2-20 μJ, a repetition rate of 1-500 kHz, and atotal energy of less than 40 J.
 16. The method of claim 15, wherein thelaser pulses have a wavelength of 1030 nm, a pulse width of 400 fs, apulse energy of 9 μJ, a repetition rate of 6-24 kHz, and a total energyof 10-40 J.
 17. The method of claim 15, further comprising, prior to theirradiating step: operating an imaging system to image structures of thevitreous humor; determining outer boundaries of the portion of thevitreous humor for treatment; and defining a scan pattern for scanningthe focal spot of the pulsed laser beam within the portion of thevitreous humor.